Life history and description of immature stages of Trupanea arizonensis Malloch (Diptera : Tephritidae) on Trixis californica Kellogg var. californica (Asteraceae) in southern California

Trupanea arizonensis Malloch is a monophagous, univoltine fruit fly (Dipter a: Tephritidae) infesting flower heads of Trixis californica Kellogg var. c alifornica (Asteraceae) in southern California. The egg, first- and third-i nstar larvae, and puparia are described and figured for the first time. As with each of the eight other Trupanea species previously studied, the later al spiracular complex of the third instar is unique to T. arizonensis, comp rising three verruciform sensilla on the meso- and metathorax and two verru ciform sensilla on each abdominal segment. The third instar of T. arizonens is also differs from those of other Trupanea species previously studied in that both the meso-and metathorax are circumscribed by verruciform sensilla . The life cycle is of the aggregative type; whereby, the adults are long-l ived and comprise the over-summering and over-wintering stage that returns with winter rainfall to aggregate on regrowing host plants for mating, and for oviposition during spring in the preblossom flower heads. The first ins tar tunneled into a single floral tube or ovule of a single immature floret , and each second and third instar continued its development by feeding pri ncipally on sap conducted to the excavated distal end of the same, then sli ghtly stunted ovule. Pupariation occurs in the open flower heads, within wh ich an average of 13% of the achenes were destroyed among heads containing puparia. Pteromalus sp. (Hymenoptera: Pteromalidae) was reared from individ ual puparia of T. arizonensis as a solitary, larval-pupal endoparasitoid.